Heat dissipation element with heat resistant mechanism

ABSTRACT

A heat dissipation element with a heat resistant mechanism is provided. The heat dissipation element is a heat pipe, a loop-type heat pipe or a vapor chamber. A heat resistant layer is properly formed on an inner side or an outer side of the heat dissipation element. Consequently, while the heat is transferred, the tactile temperature of the handheld electronic device is not influenced.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/424,012 filed Nov. 18, 2016, the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat dissipation element, and moreparticularly to a heat dissipation element with a heat resistantmechanism.

BACKGROUND OF THE INVENTION

Generally, a handheld electronic device such as a mobile phone, a tabletcomputer or a small-sized NB is equipped with a two-phase heatdissipation element for removing the heat from a chip, a memory oranother electronic component of the handheld electronic device.Consequently, the handheld electronic device can be maintained in thenormal working state. For example, the two-phase heat dissipationelement includes a heat pipe, a loop-type heat pipe or a vapor chamber.

The operating principles of different two-phase heat dissipationelements are similar. For example, the two-phase heat dissipationelement absorbs or releases heat during the liquid/gas phase change orthe gas/liquid phase change of a working medium. FIG. 1A is a schematicperspective view illustrating an inner heat pipe and a heat generationelement in a conventional handheld electronic device. FIG. 1B is aschematic cross-sectional view illustrating the inner structure of theconventional handheld electronic device of FIG. 1A and taken along theline 1B-1B. As shown in FIGS. 1A and 1B, a heat dissipation elementinstalled in a handheld electronic device 1 is a heat pipe 2. The heatpipe 2 comprises a closed pipe body 21 and a capillary structure 22. Thecapillary structure 22 is disposed within the pipe body 21 and filledwith a working medium (not shown). The pipe body 21 is at least dividedinto an evaporation section (or a heat absorbing section) 21A and acondensation section (or a heat removing section) 21B. When theevaporation section 21A of the heat pipe 2 is in contact with a heatgeneration element 11 (e.g., a chip or a memory), the working mediumabsorbs the heat from the heat generation element 11. Consequently, theworking medium is changed from a liquid state to a vapor state.Moreover, in response to a pressure difference, the working medium inthe vapor state is moved toward the condensation section 21B. Then, theworking medium releases the heat in the condensation section 21B.Consequently, the working medium is condensed from the vapor state tothe liquid state. Due to the capillary action of the capillary structure22, the working liquid in the liquid state is returned from thecondensation section 21B to the evaporation section 21A. Consequently, anext liquid/gas change process is performed.

However, since the pipe body of the heat dissipation element is usuallymade of a metallic material, the heat dissipation element still has somedrawbacks. For example, while the heat is absorbed by the evaporationsection 21A and transferred to the condensation section 21B, the heat isstill exhausted to the surroundings through conduction. Under thiscircumstance, the ambient temperature near the heat dissipation elementof the handheld electronic device 1 is largely increased. Moreover, ifthe heat is transferred to the casing of the handheld electronic device1, the tactile temperature of holding the handheld electronic device 1by the user is affected.

For solving the above drawbacks, some approaches have been disclosed inthe industries. For example, a heat insulation layer is directlyattached on an inner frame of the handheld electronic device.Alternatively, a heat insulation layer is directly attached on an innerportion of the handheld electronic device near the casing. Since theavailable space inside the handheld electronic device is insufficient,it is difficult to attach the heat insulation layer. Therefore, there isa need of providing an effective approach to solve the drawbacks of theconventional technologies.

The present invention provides a novel design to solve the drawbacks ofthe conventional technologies. In accordance with the design of thepresent invention, the heat dissipation element is improved and equippedwith an effective heat resistant mechanism to reduce or avoid heatrelease during the transfer process. Consequently, the ambienttemperature near the heat dissipation element is decreased, and thetactile temperature of holding the handheld electronic device by theuser is not affected. Moreover, the heat resistant mechanism of thepresent invention is directly formed on the heat dissipation element. Incomparison with the conventional technology requiring the subsequentprocessing operation of the back-end system vendor, the wishes of thebrand manufacturer to purchase the heat dissipation element of thepresent invention will be increased.

SUMMARY OF THE INVENTION

An object of the present invention is to avoid the problem of largelyincreasing or centralizing the ambient temperature of the heatdissipation element in the handheld electronic device, so that thenormal operation of the nearby electronic component is not adverselyaffected. Moreover, the heat dissipation element does not increase thetactile temperature of the casing of the handheld electronic device. Theheat resistant mechanism is the heat dissipation element itself, isformed on the inner side of the heat dissipation element itself, or isformed on the outer side of the heat dissipation element itself.Consequently, the heat dissipation element is applied to the handheldelectronic device. The technology of the present invention can reducethe ambient temperature of the handheld electronic device or the tactiletemperature of the casing of the handheld electronic device.

In accordance with an aspect of the present invention, there is provideda heat pipe. The heat pipe includes a pipe body, a capillary structureand a heat resistant layer. The pipe body includes an evaporationsection, a heat resistant section and a condensation section. The heatresistant section is arranged between the evaporation section and thecondensation section. The capillary structure is disposed within thepipe body. The heat resistant layer is disposed within the pipe body andlocated at the heat resistant section.

In an embodiment, the capillary structure is arranged between the pipebody and the heat resistant layer.

In an embodiment, the capillary structure is a fiber bundle.

In an embodiment, the capillary structure is a fiber bundle. The heatresistant layer is located beside the fiber bundle. Moreover, the heatresistant layer and the fiber bundle are not overlapped with each other.

In accordance with an aspect of the present invention, there is provideda heat pipe. The heat pipe is in contact with a heat generation element.The heat pipe includes a pipe body, a capillary structure and a heatresistant layer. The pipe body includes an evaporation section and acondensation section. The capillary structure is disposed within thepipe body. The heat resistant layer is disposed within the pipe body.The pipe body has a far side away from the heat generation element. Theheat resistant layer is located at the far side of the pipe body.

In an embodiment, the heat resistant layer is formed on an inner side ofthe capillary structure.

In an embodiment, the heat resistant layer is located at the evaporationsection or the condensation section of the pipe body.

In accordance with an aspect of the present invention, there is provideda loop-type heat pipe. The loop-type heat pipe is in contact with a heatgeneration element. The loop-type heat pipe includes a top plate and abottom plate. The bottom plate is in contact with the heat generationelement. The top plate and the bottom plate are stacked on each other todefine an evaporation section, a vapor channel, a condensation sectionand a liquid channel. A thermal conductivity of the bottom plate ishigher than a thermal conductivity of the top plate.

In accordance with an aspect of the present invention, there is provideda loop-type heat pipe. The loop-type heat pipe is in contact with a heatgeneration element. The loop-type heat pipe includes a top plate, abottom plate, a vapor channel and a liquid channel. The bottom plate isin contact with the heat generation element. The top plate and thebottom plate are stacked on each other to define an evaporation sectionand a condensation section. A thermal conductivity of the bottom plateis higher than a thermal conductivity of the top plate. The vaporchannel is connected with the evaporation section and the condensationsection. The liquid channel is connected with the condensation sectionand the evaporation section.

In accordance with an aspect of the present invention, there is provideda vapor chamber. The vapor chamber is in contact with a heat generationelement. The vapor chamber includes a top thin plate and a bottom thinplate. The bottom thin plate is in contact with the heat generationelement. A thermal conductivity of the bottom thin plate is higher thana thermal conductivity of the top thin plate.

In accordance with an aspect of the present invention, there is provideda vapor chamber. The vapor chamber is in contact with a heat generationelement. The vapor chamber includes a top thin plate, a bottom thinplate and a heat resistant layer. The bottom thin plate is in contactwith the heat generation element. The heat resistant layer is formed onan inner side of the top thin plate.

The above objects and advantages of the present invention will becomemore readily apparent to those ordinarily skilled in the art afterreviewing the following detailed description and accompanying drawings,in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view illustrating an inner heat pipeand a heat generation element in a conventional handheld electronicdevice;

FIG. 1B is a schematic cross-sectional view illustrating the innerstructure of the conventional handheld electronic device of FIG. 1A andtaken along the line 1B-1B;

FIG. 2A is a schematic perspective view illustrating a heat dissipationelement (e.g., a heat pipe) according to a first embodiment of thepresent invention and a handheld electronic device with the heatdissipation element;

FIG. 2B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 2A and taken alongthe line 2B-2B;

FIGS. 3A-3E schematically illustrate some variant examples of the heatdissipation element (e.g., a heat pipe) of the first embodimentinstalled in the handheld electronic device;

FIG. 4A is a schematic perspective view illustrating a heat dissipationelement (e.g., a heat pipe) according to a second embodiment of thepresent invention and a handheld electronic device using the heatdissipation element;

FIG. 4B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 4A and taken alongthe line 4B-4B;

FIGS. 4C and 4D schematically illustrate some variant examples of theheat dissipation element (e.g., a heat pipe) of the second embodimentinstalled in the handheld electronic device;

FIG. 5A is a schematic perspective view illustrating a heat dissipationelement (e.g., a loop-type heat pipe) according to a third embodiment ofthe present invention and a handheld electronic device using the heatdissipation element;

FIG. 5B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 5A and taken alongthe line 5B-5B;

FIG. 6A is a schematic perspective view illustrating a heat dissipationelement (e.g., a loop-type heat pipe) according to a fourth embodimentof the present invention and a handheld electronic device using the heatdissipation element;

FIG. 6B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 6A and taken alongthe line 6B-6B;

FIG. 7A is a schematic perspective view illustrating a heat dissipationelement (e.g., a loop-type heat pipe) according to a fifth embodiment ofthe present invention and a handheld electronic device using the heatdissipation element;

FIG. 7B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 7A and taken alongthe line 7B-7B;

FIG. 7C schematically illustrates a variant example of the heatdissipation element (e.g., a loop-type heat pipe) of the fifthembodiment installed in the handheld electronic device;

FIG. 8A is a schematic perspective view illustrating a heat dissipationelement (e.g., a vapor chamber) according to a sixth embodiment of thepresent invention and a handheld electronic device using the heatdissipation element;

FIG. 8B is a schematic cross-sectional view illustrating the innerstructure of the handheld electronic device of FIG. 8A and taken alongthe line 8B-8B; and

FIGS. 8C and 8D schematically illustrate some variant examples of theheat dissipation element (e.g., a vapor chamber) of the sixth embodimentinstalled in the handheld electronic device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer to FIGS. 2A and 2B. FIG. 2A is a schematic perspective viewillustrating a heat dissipation element (e.g., a heat pipe) according toa first embodiment of the present invention and a handheld electronicdevice with the heat dissipation element. FIG. 2B is a schematiccross-sectional view illustrating the inner structure of the handheldelectronic device of FIG. 2A and taken along the line 2B-2B. In thisembodiment, the heat dissipation element is a heat pipe 2. The innerportion of the handheld electronic device 1 comprises an accommodationspace. The accommodation space is defined by a backside wall 1A, alateral wall 1B and a front wall 1C. The heat pipe 2 comprises a closedpipe body 21 and a capillary structure 22. The capillary structure 22 isdisposed within the pipe body 21 and filled with a working medium (notshown). The pipe body 21 is at least divided into an evaporation section(or a heat absorbing section) 21A, a heat resistant section 21C and acondensation section (or a heat removing section) 21B. When theevaporation section 21A of the heat pipe 2 is in contact with a heatgeneration element 11 (e.g., a chip or a memory), the working mediumabsorbs the heat from the heat generation element 11. Consequently, theworking medium is changed from a liquid state to a vapor state.Moreover, in response to a pressure difference, the working medium inthe vapor state is moved toward the condensation section 21B through theheat resistant section 21C. The condensation section 21B itself canremove the heat. Optionally, the condensation section 21B is incooperation with another heat dissipation mechanism (e.g., a heat sink 3as shown in the drawing) to remove the heat. Consequently, the workingmedium in the condensation section 21B is condensed from the vapor stateto the liquid state. Due to the capillary action of the capillarystructure 22, the working liquid in the liquid state is returned fromthe condensation section 21B to the evaporation section 21A.Consequently, a next liquid/gas change process is performed.

In accordance with a feature of this embodiment, the heat pipe 2 isfurther equipped with a heat resistant layer 23. The heat resistantlayer 23 is located at the heat resistant section 21C between theevaporation section 21A and the condensation section 21B and arrangedaround the pipe body 21. Consequently, while the working medium in theheat pipe 2 is transferred from the evaporation section 21A to thecondensation section 21B, the heat can be transferred to the pipe body21. Moreover, since the heat resistant layer 23 is arranged around thepipe body 21, the heat cannot be transferred along the radial direction.That is, the heat is guided to be transferred toward the condensationsection 21B along the axial direction. Due to the heat resistant layer23, the ambient temperature of an electronic component 12 near the heatresistant section 21C of the heat pipe 2 is not increased by the heatpipe 2, and the electronic component 12 is maintained in the normalworking state. In this embodiment as shown in FIG. 2B, the heat pipe 2is installed in the handheld electronic device 1 and arranged near thebackside wall 1A of the casing. Consequently, the tactile temperaturenear the backside wall 1A of the casing is not locally or intensivelyincreased by the heat dissipation element.

In the first embodiment, the heat resistant layer 23 is formed on theouter side of the pipe body 21 of the heat pipe 2. Alternatively, theheat resistant layer 23 is formed on the inner side of the pipe body 21.FIGS. 3A-3E schematically illustrate some variant examples of the heatdissipation element of the first embodiment installed in the handheldelectronic device. As mentioned above, the capillary structure 22 isdisposed within the pipe body 21 of the heat pipe 2. Consequently, theforming sequences, the relative positions and the structures of the heatresistant layer 23 and the capillary structure 22 are diversified andnot restricted. Please refer to FIG. 3A. After the capillary structure22 is formed on the inner side of the pipe body 21 of the heat pipe 2,the heat resistant layer 23 is formed on the inner side of the capillarystructure 22. That is, the heat pipe 2 is a three-layered structure thatcomprises the pipe body 21, the capillary structure 22 and the heatresistant layer 23 from outside to inside. Please refer to FIG. 3B.After the heat resistant layer 23 is formed on the inner side of thepipe body 21 of the heat pipe 2, the capillary structure 22 is formed onthe inner side of the heat resistant layer 23. That is, the heat pipe 2is a three-layered structure that comprises the pipe body 21, the heatresistant layer 23 and the capillary structure 22 from outside toinside. There are many types of capillary structures. For example, thecapillary structure includes a sintered capillary structure, a recessedcapillary structure, a mesh-type capillary structure or a fiber-typecapillary structure. In case that the inner portion of the pipe bodyalong the radial direction is not completely occupied by the capillarystructure, the three-layered structure cannot be obviously defined bythe pipe body, the capillary structure and the heat resistant layer. Forexample, as shown in FIG. 3C, a fiber bundle 22A is used as thecapillary structure of the heat pipe 2, the heat resistant layer 23 islocated beside the fiber bundle 22A, which is disposed within the pipebody 21 of the heat pipe 2. Moreover, the heat resistant layer 23 andthe fiber bundle 22A are not overlapped with each other. Please refer toFIG. 3D. After the heat resistant layer 23 is formed on the inner sideof the pipe body 21 of the heat pipe 2, the fiber bundle 22A is placedin the inner side of the heat resistant layer 23.

In an embodiment, the heat resistant layer and the capillary structureare two individual components structurally. Alternatively, the heatresistant layer and the capillary structure are combined as a singlecomponent, or the heat resistant layer and the capillary structure areformed as a structure with the functions of the two components. Forexample, a capillary structure with a low thermal conductivity toprovide the function of the heat resistant layer or a heat resistantlayer with a capillary structure is feasible. Please refer to FIG. 3E.After the heat resistant layer 23 is formed on the inner side of thepipe body 21 of the heat pipe 2, the heat resistant layer 23 is machinedto create a recessed structure 22B on the surface of the heat resistantlayer 23. Under this circumstance, the heat resistant layer not only hasthe heat resistant efficacy but also provides the structure and functionof the capillary structure.

In the first embodiment, the heat resistant layer is located at the heatresistance section. It is noted that the position of the heat resistantlayer is not restricted to the heat resistance section. The heatresistant layer may be located at the evaporation section of the heatpipe or located at the condensation section of the heat pipe as long asthe normal heat absorbing efficacy of the evaporation section and thenormal heat radiating efficacy of the condensation section are notadversely affected.

Please refer to FIGS. 4A and 4B. FIG. 4A is a schematic perspective viewillustrating a heat dissipation element (e.g., a heat pipe) according toa second embodiment of the present invention and a handheld electronicdevice using the heat dissipation element. FIG. 4B is a schematiccross-sectional view illustrating the inner structure of the handheldelectronic device of FIG. 4A and taken along the line 4B-4B. In thisembodiment, the heat dissipation element is a heat pipe 2. Thearrangement of the heat pipe 2 in the handheld electronic device 1 andthe relationships between the heat pipe 2 and the adjacent electroniccomponents 11, 12 are similar to those of the first embodiment, and arenot redundantly described herein. In the heat pipe 2 of this embodiment,the heat resistant layer 23 is located at the evaporation section 21A orthe condensation section 21B of the heat pipe 2.

In case that the heat is absorbed by a surface of the heat pipe in theevaporation section, a portion of the heat is radiated to thesurroundings from another surface of the heat pipe and the tactiletemperature of the casing of the handheld electronic device is increasedor centralized. For solving this drawback, the heat pipe of the secondembodiment is further improved. In this embodiment, the heat resistantlayer is located at the evaporation section of the heat pipe. However,the heat resistant layer is formed on a specified site where the pipebody of the heat pipe is not in direct thermal contact with the heatgeneration element. Consequently, the normal heat absorbing efficacy ofthe heat pipe can be maintained. Please refer to FIGS. 4A and 4B. Inthis embodiment, the heat resistant layer 23 is formed on an outer sideof the pipe body 21 of the heat pipe 2 corresponding to the evaporationsection 21A. The heat pipe 2 has a far side away from the heatgeneration element 11, and the heat resistant layer 23 is located at thefar side of the heat pipe 2. As shown in FIG. 4A, the heat pipe 2 iscovered by the heat resistant layer 23 along a horizontal direction. Forexample, the far side of the heat pipe 2 is partially covered by theheat resistant layer 23, and the both ends of the heat pipe 2 areexposed. Alternatively, the far side of the pipe body 21 of the heatpipe 2 is completely covered by the heat resistant layer 23. That is,the both ends of the heat pipe 2 are also covered. As shown in FIG. 4B,the pipe body 21 is covered by the heat resistant layer 23 along avertical direction. The far side of the heat pipe 2 is covered by theheat resistant layer 23 from the top surface of the heat pipe 2, but theheat resistant layer 23 is not extended to the bottom surface of theheat pipe 2. Consequently, the thermal contact between the heat pipe 2and the heat generation element 11 is not affected. The above design hasthe following advantages. After the heat is absorbed by the heat pipe 2in the evaporation section 21A, the possibility of directly transferringthe heat to the casing of the handheld electronic device 1 (e.g., thebackside wall 1A of the handheld electronic device 1) is reduced orminimized. Consequently, the tactile temperature of the casing of thehandheld electronic device 1 corresponding to the evaporation section21A of the heat pipe 2 is not largely increased or centralized.

In the second embodiment, the heat resistant layer 23 is formed on theouter side of the pipe body 21 of the heat pipe 2 corresponding to theevaporation section 21A. Alternatively, the heat resistant layer 23 isformed on an inner side of the pipe body 21 of the heat pipe 2corresponding to the evaporation section 21A, and the heat resistantlayer 23 is located at the far side of the heat pipe 2 away from theheat generation element 11. FIGS. 4C and 4D schematically illustratesome variant examples of the heat dissipation element (e.g., a heatpipe) of the second embodiment installed in the handheld electronicdevice. Please refer to FIG. 4C. After the capillary structure 22 isformed on the inner side of the pipe body 21 of the heat pipe 2, theheat resistant layer 23 is formed on the inner side of the capillarystructure 22. Please refer to FIG. 4D. After the heat resistant layer 23is formed on the inner side of the pipe body 21 of the heat pipe 2, thecapillary structure 22 is formed on the inner side of the heat resistantlayer 23 and the inner side of the pipe body 21. In the above twodesigns, the heat resistant layer 23 is located at the far side of theheat pipe 2 away from the heat generation element 11. Consequently, thenormal heat absorbing efficacy of the heat pipe 2 can be maintained. Thecapillary structure 22 used in this embodiment is similar to that of thefirst embodiment. That is, the fiber bundle or the recessed capillarystructure is suitably used as the capillary structure 22 of the secondembodiment while the teachings about the heat resistant concept of thefirst embodiment are retained.

As mentioned above, the heat resistant layer 23 is located at theevaporation section 21A of the heat pipe 2. In another design, the heatresistant layer 23 is located at the condensation section 21B of theheat pipe 2. The region covered by the heat resistant layer 23 or theway of forming the heat resistant layer 23 on the inner side or theouter side of the heat pipe 2 is similar to that of forming the heatresistant layer 23 on the evaporation section 21A of the heat pipe 2.That is, the heat pipe 2 in the condensation section is partially orcompletely covered by the heat resistant layer 23 along the horizontaldirection. Similarly, the region covered by the heat resistant layer 23along the vertical position is a specified site where the heat pipe isnot in direct thermal contact with the heat sink 3 in the condensationsection 21B. Consequently, the normal heat radiating efficacy of theheat pipe 2 can be maintained. In case that the evaporation section 21A,the heat resistant section 21C and the condensation section 21B of theheat pipe 2 near the casing of the handheld electronic device 1 are allcovered by the heat resistant layer 23, the possibility of transferringthe heat to the casing of the handheld electronic device 1 is largelyreduced. Consequently, the tactile temperature of the casing of thehandheld electronic device 1 is controlled to be in a more suitablerange.

The concepts of the present invention can be also applied to other heatdissipation element such as a loop-type heat pipe or a vapor chamber.Please refer to FIGS. 5A and 5B. FIG. 5A is a schematic perspective viewillustrating a heat dissipation element (e.g., a loop-type heat pipe)according to a third embodiment of the present invention and a handheldelectronic device using the heat dissipation element. FIG. 5B is aschematic cross-sectional view illustrating the inner structure of thehandheld electronic device of FIG. 5A and taken along the line 5B-5B.

In this embodiment, the heat dissipation element is a loop-type heatpipe 4. The operating principles of the loop-type heat pipe are similarto those of the heat pipe. In comparison with the appearance of the heatpipe, the working medium in the loop-type heat pipe is continuouslycirculated within a closed loop along a single direction. In thisembodiment, the loop-type heat pipe 4 comprises an evaporation section4A, a vapor channel 4B, a condensation section 4C and a liquid channel4D. In the heat resistant mechanism of the loop-type heat pipe 4, theheat resistant layer 41 is formed on an outer side or an inner side ofthe vapor channel 4B. As shown in FIGS. 5A and 5B, the heat resistantlayer 41 is arranged around the vapor channel 4B. Consequently, whilethe heat is transferred to the condensation section 41C, the heat is notreleased to the surroundings to influence the electronic component 12 ofthe handheld electronic device 1 near the vapor channel 4B, or the heatis not externally released to the casing of the handheld electronicdevice 1 to influence the tactile temperature. Like the first embodimentand the second embodiment, the heat resistant layer is formed on theinner side of the vapor channel 4B of the loop-type heat pipe 4 of thethird embodiment.

As mentioned above in the third embodiment, the heat resistant layer isformed on the outer side or the inner side of the vapor channel of theloop-type heat pipe. In another design, the heat resistant layer isarranged around the evaporation section, the condensation section oreven the liquid channel of the loop-type heat pipe as long as the normalheat absorbing efficacy of the evaporation section and the normal heatradiating efficacy of the condensation section are not adverselyaffected.

Please refer to FIGS. 6A and 6B. FIG. 6A is a schematic perspective viewillustrating a heat dissipation element (e.g., a loop-type heat pipe)according to a fourth embodiment of the present invention and a handheldelectronic device using the heat dissipation element. FIG. 6B is aschematic cross-sectional view illustrating the inner structure of thehandheld electronic device of FIG. 6A and taken along the line 6B-6B. Incase that the heat is absorbed by a surface of the loop-type heat pipein the evaporation section, a portion of the heat is radiated to thesurroundings from another surface of the loop-type heat pipe and thetactile temperature of the casing of the handheld electronic device isincreased or centralized. For solving this drawback, the loop-type heatpipe of the fourth embodiment is further improved. In this embodiment,the heat resistant layer is located at the evaporation section of theloop-type heat pipe. However, the heat resistant layer is formed on aspecified site where the pipe body of the loop-type heat pipe is not indirect thermal contact with the heat generation element. Consequently,the normal heat absorbing efficacy of the loop-type heat pipe can bemaintained. Please refer to FIGS. 6A and 6B. In this embodiment, theheat resistant layer 41 is formed on an outer side of the loop-type heatpipe 4 corresponding to the evaporation section 4A. The loop-type heatpipe 4 has a far side away from the heat generation element 11, and theheat resistant layer 41 is located at the far side of the loop-type heatpipe 4. As shown in FIG. 6A, the loop-type heat pipe 4 is covered by theheat resistant layer 41 along a horizontal direction. For example, thefar side of the loop-type heat pipe 4 is partially or completely coveredby the heat resistant layer 41 as long as the normal heat absorbingefficacy of the evaporation section is not adversely affected. The abovedesign has the following advantages. After the heat is absorbed by theloop-type heat pipe 4 in the evaporation section 4A, the possibility ofdirectly transferring the heat to the casing of the handheld electronicdevice 1 (e.g., the backside wall 1A of the handheld electronic device1) is reduced or minimized. Consequently, the tactile temperature of thecasing of the handheld electronic device 1 corresponding to theevaporation section 4A of the loop-type heat pipe 4 is not largelyincreased or centralized.

As mentioned above, the heat resistant layer 41 is located at theevaporation section 4A of the loop-type heat pipe 4. In another design,the heat resistant layer 41 is located at the condensation section 4C ofthe loop-type heat pipe 4. The loop-type heat pipe 4 in the condensationsection 4C is partially or completely covered by the heat resistantlayer along the horizontal direction. Similarly, the region covered bythe heat resistant layer is a specified site where the condensationsection is not in direct thermal contact with other heat dissipationelement (e.g., the heat sink 3). Consequently, the normal heat radiatingefficacy of the loop-type heat pipe 4 can be maintained. In case thatthe evaporation section 4A, the vapor channel 4B, the condensationsection 4C and the liquid channel 4D of the loop-type heat pipe 4 nearthe casing of the handheld electronic device 1 are all covered by theheat resistant layer 41, the possibility of transferring the heat to thecasing of the handheld electronic device 1 is largely reduced.Consequently, the tactile temperature of the casing of the handheldelectronic device 1 is controlled to be in a more suitable range.

In the third embodiment and the fourth embodiment, an additional heatresistant mechanism is installed on the loop-type heat pipe. The presentinvention further provides a loop-type heat pipe with a heat resistantmechanism. Please refer to FIGS. 7A and 7B. FIG. 7A is a schematicperspective view illustrating a heat dissipation element (e.g., aloop-type heat pipe) according to a fifth embodiment of the presentinvention and a handheld electronic device using the heat dissipationelement. FIG. 7B is a schematic cross-sectional view illustrating theinner structure of the handheld electronic device of FIG. 7A and takenalong the line 7B-7B. In case that the heat is absorbed by a surface ofthe loop-type heat pipe in the evaporation section, a portion of theheat is radiated to the surroundings from another surface of theloop-type heat pipe and the tactile temperature of the casing of thehandheld electronic device is increased or centralized. For solving thisdrawback, the loop-type heat pipe of the fifth embodiment is furtherimproved. In this embodiment, the loop-type heat pipe 4 comprises a topplate 42 and a bottom plate 43. The thermal conductivity of the bottomplate 43 is higher than the thermal conductivity of the top plate 42, orthe top plate 42 is made of a material with a lower thermalconductivity. In this embodiment, the bottom plate 43 is in directcontact with the heat generation element 11. After the heat of the heatgeneration element 11 is absorbed by the bottom plate in the evaporationsection 4A, the heat is not easily transferred to the casing of thehandheld electronic device 1 (e.g., the backside wall 1A of the handheldelectronic device 1) through the top plate 42 because the thermalconductivity of the top plate 42 is lower. Consequently, the tactiletemperature of the casing of the handheld electronic device 1 near theevaporation section is controlled to be in a more suitable range.Moreover, the top plate 42 with the lower thermal conductivity is alsolocated at the vapor channel 4B and the condensation section 4C of theloop-type heat pipe 4. Since the heat is not easily transferred to thecasing of the handheld electronic device 1 (e.g., the backside wall 1Aof the handheld electronic device 1) through the top plate 42, thetactile temperature of the casing of the handheld electronic device 1near the vapor channel 4B and the condensation section 4C is controlledto be in a more suitable range. Moreover, the condensation section 4C ofthe loop-type heat pipe 4 is still able to dissipate heat normally. Forexample, the heat is transferred along the horizontal direction or theheat is further dissipated by another heat dissipation mechanism (e.g.,the underlying heat sink 3).

As shown in FIGS. 7A and 7B, the top plate 42 and the bottom plate 43are stacked on each other to define the evaporation section, the vaporchannel, the condensation section and the liquid channel of theloop-type heat pipe. FIG. 7C schematically illustrates a variant exampleof the heat dissipation element (e.g., a loop-type heat pipe) of thefifth embodiment installed in the handheld electronic device. As shownin FIG. 7C, the evaporation section 4A of the loop-type heat pipe 4 is acombination of a top plate 4A1 and a bottom plate 4A2, or thecondensation section 4C of the loop-type heat pipe 4 is a combination ofa top plate 4C1 and a bottom plate 4C2. The vapor channel 4B between theevaporation section 4A and the condensation section 4C and the liquidchannel 4D between the condensation section 4C and the evaporationsection 4A are not divided into two layers. That is, the vapor channel4B and the liquid channel 4D are tubes that are made of the samematerial. Since the bottom plate 4A2 in the evaporation section 4A is incontact with the heat generation element 11, the thermal conductivity ofthe bottom plate 4A2 is higher than the thermal conductivity of the topplate 4A1, or the thermal conductivity of the bottom plate 4A2 is higherthan the thermal conductivity of the vapor channel 4B. In thisembodiment, the bottom plate 4A2 is in direct contact with the heatgeneration element 11. After the heat of the heat generation element 11is absorbed by the bottom plate 4A2 in the evaporation section 4A, theheat is not easily transferred to the casing of the handheld electronicdevice 1 (e.g., the backside wall 1A of the handheld electronic device1) through the top plate 4A1 or the vapor channel 4B because the thermalconductivity of the top plate 4A1 is lower or the thermal conductivityof the vapor channel 4B is lower. As mentioned above, the condensationsection 4C of the loop-type heat pipe 4 is a combination of the topplate 4C1 and the bottom plate 4C2. Similarly, the thermal conductivityof the bottom plate 4C2 is higher than the thermal conductivity of thetop plate 4C1, or the thermal conductivity of the bottom plate 4CA2 ishigher than the thermal conductivity of the liquid channel 4D. Since theheat is not easily transferred to the casing of the handheld electronicdevice 1 (e.g., the backside wall 1A of the handheld electronic device1) through the top plate 4C1 or the liquid channel 4D, the heatresistant efficacy is enhanced.

In addition to the heat pipe and the loop-type heat pipe, the heatresistant mechanism is applied to a vapor chamber and installed in thehandheld electronic device. FIG. 8A is a schematic perspective viewillustrating a heat dissipation element (e.g., a vapor chamber)according to a sixth embodiment of the present invention and a handheldelectronic device using the heat dissipation element. FIG. 8B is aschematic cross-sectional view illustrating the inner structure of thehandheld electronic device of FIG. 8A and taken along the line 8B-8B.FIGS. 8C and 8D schematically illustrate some variant examples of theheat dissipation element (e.g., a vapor chamber) of the sixth embodimentinstalled in the handheld electronic device.

The operating principles of the vapor chamber 5 are similar to those ofthe heat pipe. The heat pipe is used for transferring heat linearlyalong a one-dimensional direction. Whereas, the vapor chamber 5 is usedfor transferring heat along a two-dimensional direction. In thisembodiment, the vapor chamber 5 comprises a top thin plate 51 and abottom thin plate 52. The bottom thin plate 52 is in contact with theheat generation element 11. The heat resistant mechanism for the vaporchamber 5 of the present invention has various types. In the example ofFIG. 8B, the vapor chamber 5 is a combination of the top thin plate 51and the bottom thin plate 52. The thermal conductivity of the bottomthin plate 52 is higher than the thermal conductivity of the top thinplate 51, or the top thin plate 51 is made of a material with a lowerthermal conductivity. Consequently, while the heat is transferred andreleased, the heat is not centralized to the top thin plate 51 of thevapor chamber 5 or the center of the top thin plate 51. That is, theheat can be transferred along the horizontal direction more uniformly.Due to the heat resistant mechanism of the present invention, theambient temperature outside the top thin plate 51 or the tactiletemperature of the casing of the handheld electronic device near the topthin plate 51 (e.g., the backside wall 1A of the handheld electronicdevice 1) is improved or controlled. As mentioned above, the thermalconductivity of the top thin plate and the thermal conductivity of thebottom thin plate are different. Moreover, the above heat resistantmechanisms of the heat pipe and the loop-type heat pipe may be appliedto the vapor chamber. As shown in FIG. 8C, the vapor chamber 5 is acombination of the top thin plate 51 and the bottom thin plate 52.Moreover, a heat resistant layer 53 is formed on an outer side of thetop thin plate 51 and arranged near the casing of the handheldelectronic device 1. As shown in FIG. 8D, the heat resistant layer 53 isdisposed within the vapor chamber 5 and formed on an inner side of thetop thin plate 51. Consequently, while the heat is transferred andreleased, the heat is not transferred to the casing of the handheldelectronic device 1. Consequently, the tactile temperature is controlledto be in a more suitable range

In accordance with the present invention, the heat resistant layer ismade of a material with low thermal conductivity. For example, the heatresistant layer is made of aluminum, glass fiber, ceramic, rubber,asbestos, rock wool, aerogel, stainless steel, ceramic paint, aerogelpaint, insulation resin paint or silicate paint. The way of forming theheat resistant layer is not restricted. For example, the heat resistantlayer is produced by a coating process, a sputtering process, adeposition process, a sintering process, an etching process, ananodizing process, an electroplating process, an electroless platingprocess or an attaching process. Alternatively, the heat resistant layeris firstly formed as a hollow tube, and then the hollow tube is sheathedaround the heat pipe.

The heat dissipation element and the heat generation component withinthe handheld electronic component are in thermal contact with eachother. The structure of the thermal contact includes a direction contactmechanism or an indirect contact mechanism. In some embodiments, athermal grease, a heat dissipation plate or a heat conduction block isarranged between the heat dissipation element and the heat generationelement.

In the above embodiments and associated drawings, the relative positionsbetween the casing of the handheld electronic device and the heatdissipation element and the installation of the heat dissipation elementin the handheld electronic device are not restricted. It is noted thatthe heat resistant mechanism of the present invention may be applied toan electronic product and modified according to practical requirements.For example, in case that the installation position of the heatdissipation element is at the edge frame near the two lateral walls 1B,the tactile temperature of the two lateral walls of the handheldelectronic device is not very high. Similarly, the technology of thepresent invention can be employed to reduce the tactile temperature ofthe top edge frame, the bottom edge frame or the front wall 1C (e.g.,the display screen) of the handheld electronic device.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiments. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all modifications and similarstructures.

What is claimed is:
 1. A heat pipe, comprising: a pipe body comprisingan evaporation section, a heat resistant section and a condensationsection, wherein the heat resistant section is arranged between theevaporation section and the condensation section; a capillary structuredisposed within the pipe body; and a heat resistant layer disposedwithin the pipe body and located at the heat resistant section.
 2. Theheat pipe according to claim 1, wherein the capillary structure isarranged between the pipe body and the heat resistant layer.
 3. The heatpipe according to claim 1, wherein the capillary structure is a fiberbundle.
 4. The heat pipe according to claim 1, wherein the capillarystructure is a fiber bundle, wherein the heat resistant layer is locatedbeside the fiber bundle, and the heat resistant layer and the fiberbundle are not overlapped with each other.
 5. A heat pipe in contactwith a heat generation element, the heat pipe comprising: a pipe bodycomprising an evaporation section and a condensation section; acapillary structure disposed within the pipe body; and a heat resistantlayer disposed within the pipe body, wherein the pipe body has a farside away from the heat generation element, and the heat resistant layeris located at the far side of the pipe body.
 6. The heat pipe accordingto claim 5, wherein the heat resistant layer is formed on an inner sideof the capillary structure.
 7. The heat pipe according to claim 5,wherein the heat resistant layer is located at the evaporation sectionor the condensation section of the pipe body.
 8. A loop-type heat pipein contact with a heat generation element, the loop-type heat pipecomprising: a top plate; and a bottom plate in contact with the heatgeneration element, wherein the top plate and the bottom plate arestacked on each other to define an evaporation section, a vapor channel,a condensation section and a liquid channel, wherein a thermalconductivity of the bottom plate is higher than a thermal conductivityof the top plate.
 9. A loop-type heat pipe in contact with a heatgeneration element, the loop-type heat pipe comprising: a top plate; abottom plate in contact with the heat generation element, wherein thetop plate and the bottom plate are stacked on each other to define anevaporation section and a condensation section, wherein a thermalconductivity of the bottom plate is higher than a thermal conductivityof the top plate; a vapor channel connected with the evaporation sectionand the condensation section; and a liquid channel connected with thecondensation section and the evaporation section.
 10. A vapor chamber incontact with a heat generation element, the vapor chamber comprising: atop thin plate; and a bottom thin plate in contact with the heatgeneration element, wherein a thermal conductivity of the bottom thinplate is higher than a thermal conductivity of the top thin plate.
 11. Avapor chamber in contact with a heat generation element, the vaporchamber comprising: a top thin plate; and a bottom thin plate in contactwith the heat generation element; and a heat resistant layer formed onan inner side of the top thin plate.